The present invention relates to a process for preparing a "retort tofu" which is storable for a long period of time. More particularly, the present invention relates to a new process for preparing a retort tofu having excellent taste and texture, in which the formation of pores and syneresis do not occur, by simply adjusting specific conditions of the retort procedures.
Heretofore, it has been known that a so-called packaged tofu can be prepared by adding a suitable amount of a coagulant to soybean milk, charging the mixture into a container, sealing the container and heating it to coagulate the mixture. However, if the packaged tofu is subjected to a retort treatment in which the tofu is maintained at a high temperature of at least 100.degree. C. and a high pressure, in order to impart long-term storability to the packaged tofu, the formation of pores and the occurrence of the syneresis become quite a significant problem and further, the tofu lacks smoothness and compactness, qualities which are regarded as the life and the soul of good tofu. Therefore, the resulting tofu according to such process is inferior in quality.
For improving such process for coagulating tofu by the retort treatment, it has been proposed to use a product obtained by adjusting the pH of soybean milk and then maintaining it at a temperature of at least 115.degree. C. for a suitable period of time (see Japanese Patent Publn. No. 50941/1981) and to disperse a curd, prepared by coagulating soybean milk with an acid and/or a salt and removing the supernatant, into water, and adding egg white to the dispersion and then mixing to form a uniform dispersion, thereafter charging the dispersion into a container and heating it under high temperature and pressure conditions (see Japanese Patent Publn. No. 50940/1981) or the like.
However, all of the foregoing processes are very complicated since they require a lot of steps compared to the conventional process for the preparation of tofu. In addition, in the latter process egg white is used, which is not usually used as an ingredient of tofu and therefore, the resulting tofu cannot be regarded as a pure tofu.